This invention relates to the use of chitosan and chitosan-metal complexes to generate antimicrobial polyester-containing articles having improved wash durability.
PCT application WO 00/49219 discloses the preparation of substrates with biocidal properties. The deposition of solubilized chitosan on polyester, among other materials, followed by treatment with silver salts, reduction of the silver salt and crosslinking the chitosan is disclosed to yield a durable biocidal article. The application also discloses the crosslinking of the chitosan after it is applied, either before or after the silver salt treatment.
S. Matsukawa et al., Sen-I Gakkaishi, 51(1), 51-56 (1995) disclose the modification of polyester fabrics using chitosan. The polyester was hydrolyzed with caustic soda, neutralized with 1-% acetic acid solution, then treated with a chitosan solution and, optionally, with a crosslinking agent. This method suffers the limitations that no covalent bond is established between the chitosan and the polyester, it is a multistep process, and multiple padding of chitosan is needed to obtain the desired durability.
Huh et al., J. Appl. Polymer Sci., 81, 2769-2778 (2001) disclose grafting of acrylic acid units to a polyester article, followed by activation of the surface carboxyl groups and covalently linking chitosan. This addition of the acrylic oligomeric unit may not be desirable in many textile applications and may not be suitable as a drop-in process for textile mills.
PCT Application WO 01/88019 discloses the use of carbodiimide species to activate polyester carbonyl groups for subsequent covalent bonding with chitosan. The end carboxyl group of a polylactide or caprolactone polymer is treated with N-hydroxysuccinimide and carbodiimide to make an active ester. This active ester is then treated with chitosan to make an amide linkage. The patent does not disclose antimicrobial properties, nor the durability of such properties.